Chemically pure sodium chloride is dissolved in distilled or deionized water at a concentration of 50±5 g/L. Using a pH meter to measure the pH of the solution, you can also use a precision pH test paper calibrated with a pH meter for routine testing. The pH of the solution can be adjusted with chemically pure hydrochloric acid or sodium hydroxide. The pH value of the salt spray collection solution in the test chamber was 6.5-7.2. To avoid nozzle clogging, the solution must be filtered before use.

b. Sample

The type, number, shape, and size of the test specimens should be based on the requirements of the test overlay or basthroom sink drain product standard. If there is no standard, it can be decided in consultation with the relevant parties. Before the test, the bathroom sink drain sample must be fully cleaned. The cleaning method depends on the surface condition of the bathroom sink drain sample and the nature of the dirt. Do not use abrasives and solvents that will attack the surface of the specimen. After the sample is washed, contamination must be avoided. If the specimen is cut from the workpiece, the cover near the cutting area cannot be damaged. In addition to the regulations, the cutting area must be protected with a suitable covering, such as paint, sarcophagi, or adhesive tape.

c. Bathroom sink drain sample placement

The bathroom sink drain sample is placed in the test box with the test surface facing upwards, allowing the salt spray to settle freely on the test surface. The test surface cannot be sprayed directly by the salt spray. The angle at which the bathroom sink drain sample is placed is important. The test surface of the flat plate specimen is 15° to 30° from the vertical direction, and is 20° as far as possible. Samples with irregular surfaces (such as the entire workpiece) should also be as close as possible to the above requirements. Bathroom sink drain samples must not touch the cabinet or contact each other. The distance between the specimens should not affect the salt spray freely landing on the test surface. Drops on the specimen must not fall on other specimens. Sample holders are made of glass, plastic, and other materials. Suspended specimens shall not be made of metal. Man-made fibres, cotton fibres or other insulating materials shall be used. Drops on the holder must not fall on the specimen.

d. Test conditions

The temperature inside the spray box is 35±2°C. After the salt mist settles, after 24 h spraying, each collected solution should be 1-2 ml/h for 80 cm, 50±10 g/L sodium chloride, and pH 6.5-7.2. Through the mist in the sample area, no more use.

e. Test cycle

The time of the test should be determined according to the requirements of the test coverage or bathroom sink drain product standard; if there is no standard, it can be decided through consultation of relevant parties. The recommended test time is: 2, 6, 16, 24, 48, 96, 240, 480, 720h. The spray must not be interrupted during the specified test period. The salt spray box can only be opened when the sample is to be briefly observed. If the end point of the test depends on the time at which corrosion begins, the bathroom sink drain sample needs to be checked frequently. Therefore, these specimens cannot be tested together with specimens having a predetermined test period. The test for a predetermined period can be checked in the above cycle. However, the test surface cannot be destroyed during the inspection process. The time for the inspection of the specimens should be as short as possible.

f. Cleaning of test specimen after test

At the end of the test, remove the bathroom sink drain sample. In order to reduce the loss of corrosion products, the bathroom sink drain sample was naturally dried in the room for 0.5-1 h before cleaning. Then gently rinse with clean running water no higher than 40°C to remove the residue from the salt solution on the surface of the bathroom sink drain sample and immediately blow dry with a hair dryer.

g. Evaluation of test results

The test results are compared with the test results of specimens and specimens after corrosion test of bathroom sink drain metal and other inorganic coatings on metal substrates by the GB/T6461-2002 technical standards and the agreement between the two parties, and they are qualified within the scope of the standard, and vice versa. Failed to pass the test.